What challenges from nature does Sam face?

In My Side of the Mountain, Sam faces a number of challenges from nature, especially relating to weather and animals. Since Sam is from New York City, one of the first physical challenges he faces is the difficult and steep terrain of the Catskill Mountains.
Every day he spends in the wilderness, he must adapt to unmarked, rocky paths in the forest, steep elevations, densely-wooded territory, injuries, and the threat of poisonous insects or snakes. Likewise, Sam must defend himself against predatory animals in the wild. Although he quickly adapts to fishing and hunting, Sam faces the possibility of starvation and sickness from living in the wild. He must learn which plants and berries are edible and which are dangerous; he also has to constantly secure clean water for drinking, cooking, and cleaning.
Another clear danger Sam faces during the winter is the possibility of freezing to death. While learning how to create makeshift shelters, Sam must protect himself against the cold, wind, rain, lightning, and storms; he creates his own fireplace and even learns how to make his own clothes from animal hides.